1. FIELD OF THE INVENTION
This invention relates to rolling mills, and more particularly it is concerned with a rolling mill of the type in which work rolls of high rigidity are mounted in roll chocks disposed in a housing.
2. DESCRIPTION OF THE PRIOR ART
In recent years there has developed an increasing demand for producing more uniform thickness in rolled products. Advances made in the progress of art of automatically controlling strip thickness have made it possible to obtain substantially improved uniform thickness lengthwise of a metallic strip.
A program has been under way under our auspices for producing rolled products in which uniformity in thickness is maintained widthwise of the rolled product over the entire surface thereof. We have recently found that, by moving the pair of upper and lower intermediate rolls of a rolling mill axially thereof so that one end or forward end of each intermediate roll may coincide in position with the corresponding edge of strip material or may be disposed in the neighborhood thereof in order to reduce the bending of upper and lower work rolls into a barrel shape caused by a rolling load, it is possible to effect control of strip contour in the same manner as if the work rolls were backed up by back up rolls which are crowned in conformity with the width of the strip material. We have also found that it is possible to cope with a change in other rolling conditions than the width of strip material, e.g. the rate of rolling reduction, crowning of the rolls induced by heat builtup therein and the like, by axially moving the intermediate rolls. We have also found that the same effect can be obtained in a 4-high stand mill by axially moving the work rolls themselves or the back up rolls which back up the respective work rolls.
It will be understood that the inventions already made for the purpose of producing uniform thickness widthwise of rolled products call for varying the amounts of axial movements of the rolls in accordance with a change in rolling conditions, e.g. a variation in the width of strips fed to the mill, crowning of the rolls induced by heat built up therein or movement of strip material in a zigzag fashion along the pass line, or the like, which may occur both at the start of and during a rolling operation.
One example of rolling mills in which rolls are movable axially thereof is a Sendimir mill. A first intermediate roll moving means of this mill is arranged to be disposed parallel to the spindle for operating the upper and lower rolls disposed on the drive side of the mill. This arrangement makes the structure in the vicinity of the roll moving means complex. The roll moving device of the aforementioned construction would be unfit for use with a rolling mill of the large size which employs work rolls of relatively high rigidity and in which it is required to move the rolls axially thereof while a rolling operation is in progress, because such roll moving device must be of high capacity. Difficulty would be encountered in removing the spindles or effecting maintenance of the parts if the roll moving device of high capacity constructed as aforementioned were mounted in a rolling mill of the large size.